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Mercury 4.6L SOHC specs: 281 ci (4.6L) 8-cylinder, 3.551 x 3.543 in (90.2 x 90 mm) bore and stroke, 9.4:1 compression. Rated 190-210 hp. SOHC.
The Mercury 4.6L SOHC is close to square: 3.5512" bore against 3.5433" stroke, within 0.2%, which splits the difference between a high-revving layout and a torque layout. The 3.5433" stroke puts mean piston speed at 4,000 ft/min around 6,750 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 35.1 ci (576 cc).
9.4:1 on aluminum heads is low by modern standards and generally happy on regular pump fuel.
It is one of 6 engines in the Modular family, all of them 281 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated from 190 to 210 hp. Factory fitments include the Mercury Grand Marquis, Mercury Marauder, Mercury Cougar and 4 others.
| Displacement | 281 ci / 4.6 L |
|---|---|
| Bore | 3.5512" |
| Stroke | 3.5433" |
| Cylinders | 8 |
| Compression ratio | 9.4:1 |
| Bore/stroke ratio | 1.002 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 190–210 hp |
| Bore/stroke character | 1.002 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,543 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 35.1 ci |
| Static compression | 9.4:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| — | 190 hp | 4.6L SOHC, 4.6 SOHC, 4.6L SOHC V8, Romeo/Windsor 4.6L |
| — | 210 hp | 4.6L 2V, 4.6L SOHC |